1. Field of the Invention
The present invention relates to an apparatus and method for stripping a section of insulation covering from an insulation-covered wire at a predetermined location along the wire.
2. Related Art
FIG. 4 is a front view showing a conventional apparatus for stripping a section of insulation covering from an insulation-covered wire at a predetermined location along the wire (this apparatus will be referred to as an insulation-covering section stripping apparatus). In the conventional insulation-covering section stripping apparatus 100, an insulation-covered wire 50 is fed in a direction 104 of an arrow, and a slitting blade 101 is lowered onto the insulation-covered wire 50 to form a cut of a predetermined length in the insulation-covered wire 50 in the axial direction of the wire. Subsequently, the insulation-covered wire 50 is fed to a location of a couple of circumferential cutting blades 102, which are positioned while being spaced from each other by a predetermined distance. The insulation-covered wire 50 is circumferentially cut at two positions by the circumferential cutting blades 102. An insulation removal blade 103 is lowered onto the insulation-covered wire 50 to remove a section of insulation covering from the insulation-covered wire 50. Each circumferential cutting blade 102 includes two V-shaped blades. The insulation removal blade 103 uses a U-shaped groove. To remove the insulation-covering section, the U-shaped groove of the insulation removal blade 103 is pressed against the insulation-covered wire 50 to strip the section of the insulation covering from the wire.
Another insulation-covering section stripping 5 apparatus is known (JP-A-3-79929, U.S. Pat. No. 3,748,932). In the apparatus, an insulation-covered wire is axially cut, and circumferentially cut at two positions with circumferential cutting blades spaced by a predetermined distance. Then, the circumferential cutting blades are moved toward each other along the wire axis to separate the insulation-covering section from the wire. An additional insulation-covering section stripping apparatus is known (JP-A-56-19319). The stripping apparatus cuts an insulation-covered wire along its axial line with a heat cutter, which is heated to a temperature higher than a heat-resistant temperature of the insulation-covered wire, and strips the cut portion of the insulation covering from the wire.
Problems of the insulation-covering section stripping apparatuses mentioned above will be described. Large pressure acts on the slitting blade in cutting the insulation-covered wire in the axial direction. Wearing of the slitting blade progresses at relatively high rate. This problem is found in all of those conventional stripping apparatuses. A measure taken for this is to heat the slitting blade to a temperature higher than a heat-resistant temperature of the insulation-covered wire. The heating of the slitting blade at such a high temperature promotes the blunting of the slitting blade. This results in frequent adjustment, maintenance and exchanging of the slitting blade, and hence inefficient stripping work. An additional problem of the conventional art is that it is difficult to axially cut a thin insulation-covered wire, and to strip a section of insulation from the insulation-covered wire at a location intermediate the ends of the wire.